Sewing machine



R. A. GlANlNAZZl SEWING MACHINE May 21, 1968 Filed Sept. 23, 1966 INVENTOR United States Patent 3,384,042 SEWING MACHINE Rolando A. Gianinazzi, Geneva, Switzerland, assignor to Melina S.A., Fribourg, Switzerland, a company of Switzerland Filed Sept. 23, 1966, Ser. No. 581,635 Claims priority, application Switzerland, Oct. 12, 1965, 14,060/ 65 7 Claims. (Cl. 112-158) The present invention relates to a sewing machine for sewing with two threads, the upper thread carried by the needle and the lower thread delivered by the shuttle, a looper being intended to produce the locking of the two threads to form a stitch, a feed dog ensuring the displacement of the Work to be sewn under the presser foot.

According to the present invention a sewing machine for sewing with two threads comprises an upper thread capable of being fed by a needle, a lower thread capable of being fed by a shuttle, a looper being provided to cause the locking of the two threads to form a stitch, a feed dog ensuring the displacement of workpieces under a presser foot, the feed dog having a part capable of com ing periodically into contact with the needle and/ or the upper thread loop, during the inoperative return movement of the feed dog whilst the needle is still engaged in a needle plate, to remove the needle and/or to flatten and remove the upper thread loop from the looper and to prevent the formation of a stitch so as to increase the distance between each locked stitch relatively to the stitch length adjusted on the machine.

Such a sewing machine therefore makes it possible to produce seams which may be used in particular for tacking which is of special interest in basting garments.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partial section, taken transversely relatively to the needle plate of a portion of the sewing machine;

FIG. 2 is a plan view of the feed dog of the sewing machine;

FIG. 3 is a section of the feed dog and of an accessory shown separately;

FIG. 4 is an example of a seam with zigzag stitch capable of being made by means of a sewing machine with ornamental stitches;

FIG. 5 shows the seam capable of being effected by the sewing machine giving a seam according to FIG. 4 for tacking;

FIG. 6 is an enlarged section showing a tacking stitch;

FIG. 7 is a view of a first variation; and

FIG. 8 shows a second variation.

With reference to FIG. 1, the sewing machine shown comprises a frame 1, the lower arm or work table of which has an opening 2 with which the needle plate 3 engages. Disposed in an upper arm of this sewing machine, so as to be vertically slidable is a needle bar 4, carrying the needle 5, the needle bar also has an eyelet 6 for guiding the upper thread 7 of the thread tensioner (not shown) to the eye 8 of the needle 5. In the lower arm of the sewing machine, or under the work table thereof, is located a shuttle device 9 intended to feed the lower thread 10. This shuttle device 9 comprises a rotatable looper 11 adapted to engage the upper thread loop 7 formed at the beginning of the withdrawal of the needle 5 from the workpieces 12. The workpieces are held against the needle plate 3 by a presser foot 13.

The drive of the workpieces 12 under the presser foot 13 is efiected by means of a feed dog 14, the teeth 15 of which engage in openings provided for this purpose in the needle plate 3. The feed dog 14 is driven with a rising and falling reciprocating movement and also a transverse movement. To control the advance of the workpieces 12, the feed dog 14 is raised and then displaced in the direction of the arrow 16 to provide the drive of the workpieces 12. At the end of the driving movement, the feed dog 14 is lowered and effects a return movement in the direction opposite to the arrow 16.

When such a sewing machine is provided for automatic control of decorative stitches, it is usually fitted with cams controlling a cycle of particular stitches during each of their revolutions. In such machines cams may be mounted producing a zigzag stitch, that is to say, cams produring a lateral displacement of the needle 5 between two successive stitches. By means of such a machine it is possible to obtain the stitch shown in FIG. 4. It will be immediately understood, upon examining the stitch shown in FIG. 4, that if the locking of the upper thread 7 and lower thread 10 of the machine could be eliminated during the sewing of the stitches 17 on the right, a stitch of great amplitude could be obtained between the stitches 18 on the left. FIG. 5 shows the shape of the seam obtained in this case. The above-described machine is provided precisely to enable the periodic locking of certain stitches to be avoided during the sewing. For this purpose, the feed dog 14 of this sewing machine has a part 19 capable of coming periodically into contact with the needle 5 during the inoperative return movement of the feed dog 14 under the workpieces 12 whilst the needle 5 is still engaged in the needle plate 3.

In the first embodiment of the sewing machine, the part 19 is formed on a plate 20 (see FIGS. 2 and 3) capable of being detachably mounted on the feed dog 14 between the rows of teeth 15 thereof. When such a plate 20 is mounted on the feed dog 14, it will be immediately understood that, if the sewing machine is adjusted for zigzag stitches according to FIG. 4, each time the feed dog 14 effects its return movement under the workpieces 12 and the needle 5 makes a stitch on the right relatively to the line of stitching, the part 19 of the plate 20 causes flexion of the needle 5 as shown in FIG. 1, which flexion prevents engagement by the rotatable looper 11 in the upper thread loop 7 fed by the needle 5. Thus the stitches 17 on the right of the line of sewing will not be locked and the threads 7 and 10 will directly connect the stitches 18 on the left, as shown in FIG. 5.

When the sewing machine is to be used for normal stitching, the plate 20 is withdrawn from the feed dog 14.

In an alternative embodiment the plate 20 can be dispensed with. The driving mechanism of the feed dog 14 of this sewing machine would then comprise a cam periodically producing a movement of increased amplitude of the feed dog 14 in the return direction thereof, so as to cause a fiexion of the needle 5 by the part 19 which would then be constituted by the left edge of the centre opening 21 of the feed dog 14 (see FIG. 7). During the sewing of a normal seam, this feed dog 14 could then only effect a longitudinal movement of the amplitude N, whilst, when the mechanism controlling the movement of the feed of this machine comes into action for each stitch not locked, the feed dog 14 would be driven with an exceptional amplitude E greater than the amplitude N. FIG. 7 shows in dotted lines the position occupied by the left edge of the opening 21 at the end of the movement to the right relatively to FIG. 7 for a normal amplitude and, by chaindotted lines, the position at the end of movement to the 7 right during the control of a movement of exceptional construction with which some parts have been described with reference to FIG. 7, it will be immediately understood that with a sewing machine according to the invention it is possible to obtain a tacking stitch even if the stitching of the machine is perfectly straight stitching. In fact, with such a machine, in which the amplitude of the feed dog 14 is periodically increased, it would be possible to obtain, in a straight seam, a certain number of stitches 17 cyclically escaping the looper 11, these missed stitches being followed by locking stitches 18 aligned therewith (see FIG. 7).

It is obvious that, in order to periodically avoid the locking of certain stitches when sewing, it is possible to arrange for the part 19 of the feed dog 14 and/or of the plate 20, to flatten out and remove from the looper 11 the upper looper thread 7 without bending the needle 5.

I claim:

1. A sewing machine having two thread supplies, a needle for feeding a first thread, a shuttle for feeding a second thread, a looper for engaging said threads to form a stitch, a workforwarding device and means carried by said device for repetitively preventing and permitting said thread engagement.

2. A sewing machine as recited in claim 1 in which said needle has a mounting bar, means for reciprocating said mounting bar, means for moving said mounting bar from a first to a second position and back with respect to said shuttle, means for reciprocating, raising and lowering said workforwarding device, and means carried by said device for deflecting said needle when said mounting bar is moved to a particular one of said positions.

3. A sewing machine as recited in claim 1 in which said needle has a mounting bar, means for reciprocating said mounting bar, means for moving said bar from a first to a second position and back with respect to said shuttle, means for reciprocating, raising and lowering said workforwarding device, and means carried by said device for preventing said needle-carried thread from engaging with said looper when said needle bar is moved to a particular one of said positions.

4. A sewing machine as recited in claim 1 in which said needle has a mounting bar mounted for reciprocation, said workforwarding device is a feed dog with work-engaging teeth and means for repetitively reciprocating, raising and lowering said dog, means for periodically extending said reciprocating movement, and means carried by said dog for modifying the movement of said first thread during said extended movement so as periodically to suppress a predetermined number of stitch formation actions.

5. A sewing machine as recited in claim 1 in which said means carried by said workforwarding device is a slotted plate fastened to said device.

6. A sewing machine as recited in claim 1 in which said means is a projection on said workforwardin device, said projection defining part of a space through which said needle passes.

7. A sewing machine as recited in claim 1 in which said workforwarcling device is controlled by means of a cam, means for rotating said cam, and means moved by said cam for periodically varying the reciprocating movement of said workforwarding device.

References Qited UNITED STATES PATENTS 434,996 8/1890 Sawtell 112227 479,369 7/1892 Kern 112-227 XR 898,403 9/1908 Corey 112-227 2,083,095 6/1937 Rosenman l12241 3,340,838 9/1967 Morris 112-262 JORDAN FRANKLIN, Primary Examiner.

J. R. BOLER, Examiner. 

1. A SEWING MACHINE HAVING TWO THREAD SUPPLIES, A NEEDLE FOR FEEDING A FIRST THREAD, A SHUTTLE FOR FEEDING A SECOND THREAD, A LOOPER FOR ENGAGING SAID THREADS TO FORM A STICH, A WORKFORWARDING DEVICE AND MEANS CARRIED BY SAID DEVICE FOR REPETITIVELY PREVENTING AND PERMITTING SAID THREAD ENGAGEMENT. 